Model based automatic climate control system for an improved thermal comfort

ABSTRACT

A method of providing automatic climate control. A set point temperature input setting may be read. A cabin equivalent homogeneous temperature, computed real-time, may be compared to the set point temperature. A control value may be determined to equalize the cabin equivalent homogeneous temperature with the set point temperature.

TECHNICAL FIELD

The field to which the disclosure generally relates includes climatecontrol systems, and more particularly, includes automatic climatecontrol in heating, ventilation and air conditioning systems.

BACKGROUND

Heated, ventilated and/or air conditioned spaces exist in a variety ofenvironments and may be occupied by people, or used to contain otherthings. These spaces may be in mobile applications such as land, air andwater vehicles, or in stationary applications such as buildings andcontainers. In certain applications the spaces may include a compartmentor “cabin,” within which a person may be housed or transported. In otherapplications, “cabin” may refer generically to a contained space. Acabin may be provided with a ventilation system that supplies outsideair to the cabin, a heating system which delivers air at an elevatedtemperature to the cabin, and an air conditioning system which deliversair at a reduced temperature to the cabin. The objective of thesesystems is to provide thermal comfort to the occupants of the cabin.

It is a challenge to determine how much heating, ventilating or coolingis required in order to provide an optimum thermal environment orcomfort for all contained items such as occupants. Thermal sources mayinclude the structure or its components, the occupants or containeditems, outside air temperature and solar load, each of which may bevariable. Within this environment, air stratification, heat storage initems such as the instrument panel of a vehicle, and discharge fromnearby HVAC vents, may degrade the accuracy of the temperaturemeasurement from an in-cabin temperature sensor upon which control mayrely.

SUMMARY OF ILLUSTRATIVE VARIATIONS

A number of variations may involve a method of providing automaticclimate control. A set point temperature input may be read. A cabinequivalent homogeneous temperature may be compared to the set pointtemperature. A control value may be determined to equalize the cabinequivalent homogeneous temperature with the set point temperature.

A number of additional variations may involve method of providingautomatic climate control of a heating, ventilating and air conditioningsystem. A set point temperature input may be read. A cabin equivalenthomogeneous temperature may be calculated. The cabin equivalenthomogeneous temperature may be compared to the set point temperature. Acontrol value may be generated to equalize the cabin equivalenthomogeneous temperature with the set point temperature.

A number of other variations may involve a method of controlling an HVACsystem. A set point temperature input may be read. A cabin equivalenthomogeneous temperature may be obtained. The cabin equivalenthomogeneous temperature may be compared to the set point temperature. Acontrol error based on a difference between the cabin equivalenthomogeneous temperature and the set point temperature may be generated.A control value may be determined based on the control error. The HVACsystem may be adjusted based on the control value.

Other illustrative variations within the scope of the invention willbecome apparent from the detailed description provided herein. It shouldbe understood that the detailed description and specific examples, whiledisclosing variations within the scope of the invention, are intendedfor purposes of illustration only and are not intended to limit thescope of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

Select examples of variations within the scope of the invention willbecome more fully understood from the detailed description and theaccompanying drawings, wherein:

FIG. 1 illustrates a schematic diagram of automatic climate controlsystem according to a number of variations.

FIG. 2 illustrates a method of automatic climate control according to anumber of variations.

FIG. 3 illustrates a comfort curve graphed as comfort rating versus EHTaccording to a number of variations.

FIG. 4 illustrates a calibration curve graphed as EHT versus ambienttemperature according to a number of variations.

DETAILED DESCRIPTION OF ILLUSTRATIVE VARIATIONS

The following description of the variations is merely illustrative innature and is in no way intended to limit the scope of the invention,its application, or uses.

In a number of variations as illustrated in FIG. 1, a heating,ventilation, and air conditioning (HVAC), system 10 may be associatedwith a mobile or stationary application such as an air, land or watervehicle, a building or container, or another application, and may be anautomatic climate control system. The system 10 may include an ambientair temperature sensor 12 for measuring the temperature of externalambient air (T_(a)). A cabin air temperature sensor 14 may be providedfor measuring air temperature inside the cabin (T_(c)). A control device16 may be provided, such as in the instrument panel of the vehicle, orat another location appropriate for the application, to provide atemperature setting desired by occupants such as the driver and frontpassenger of a vehicle, which may be the set point temperature (T_(sp)).The inputs T_(a), T_(c) and T_(sp) may be provided to a controller 20.

Methods, algorithms, or parts thereof may be implemented in a computerprogram product of the controller 20 including instructions orcalculations carried on a computer readable medium for use by one ormore processors to implement one or more of the method steps orinstructions. The computer program product may include one or moresoftware programs comprised of program instructions in source code,object code, executable code or other formats; one or more firmwareprograms; or hardware description language (HDL) files; and any programrelated data. The data may include data structures, look-up tables, ordata in any other suitable format. The program instructions may includeprogram modules, routines, programs, objects, components, and/or thelike. The computer program may be executed on one processor or onmultiple processors in communication with one another.

In a number of variations, the program(s) may be embodied on computerreadable media, which can include one or more storage devices, articlesof manufacture, or the like. Illustrative computer readable media mayinclude computer system memory, e.g. RAM (random access memory), ROM(read only memory); semiconductor memory, e.g. EPROM (erasable,programmable ROM), EEPROM (electrically erasable, programmable ROM),flash memory; magnetic or optical disks or tapes; and/or the like. Thecomputer readable medium also may include computer to computerconnections, for example, when data may be transferred or provided overa network or another communications connection (either wired, wireless,or a combination thereof). Any combination(s) of the above examples isalso included within the scope of the computer-readable media. It istherefore to be understood that methods may be at least partiallyperformed by any electronic articles and/or devices capable of executinginstructions corresponding to one or more steps of the disclosedmethods.

In a number of variations the controller 20 may produce signals that maybe delivered to an HVAC blower 22 and may set the operational stateand/or speed thereof. The controller 20 may produce signals to set thetarget discharge air temperature 24 such as at the discharge of theblower 22 and closed loop feedback may be provided to the controller 20.The controller 20 may produce signals that may be delivered to set theoperational mode 26 of the HVAC system such as heating through a heatersystem, or cooling through an air conditioning system, or ventilating toprovide outside air to the cabin.

In a number of variations as illustrated in FIG. 2, a method 30 mayprovide automatic climate control based on a cabin equivalenthomogeneous temperature (EHT). The method 30 may provide for simplifiedcalibration and shorten the time needed to perform calibration and maycommence at step 32. It has been found that factors such as airstratification, heat storage in components such as the instrument panel,and vent discharge may impact the accuracy of the measured in-cabintemperature as compared to breath air temperature (i.e. air temperatureadjacent to an occupant's face). Because of this, calibration of anautomatic climate control system may be relatively challenging and timeconsuming.

In an enclosed space such as a vehicle cabin, occupant thermal comfortmay be affected by environmental parameters that influence body heatloss such as surrounding air temperature, mean radiant temperature, airvelocity, direct solar load, and humidity. One such parameter is breathair temperature which may be defined as the dry bulb temperature of theair near an occupant's face. Another parameter, mean radiant temperaturecan be defined as the uniform surface temperature of an imaginaryenclosure in which an occupant would exchange the same amount of radiantheat as in the actual non-uniform space. The factors that affect thermalcomfort are those that affect the body heat loss. The EHT is arecognized measure of the total heat loss from the human body that canbe used to characterize highly non-uniform thermal environments. It isparticularly useful in relation to a confined space such as a vehiclepassenger compartment due to the complex interaction of radiation andconvection heat fluxes. The advantage of EHT is that it expresses theeffects of combined thermal influences in a single variable that is easyto interpret and explain in relation to occupant thermal comfort. EHTmay be determined according to known methods and may be used as an inputat step 32. One such method is described in published U.S. patentapplication Ser. No. 12/179,608 titled Automatic Climate Control for aVehicle, and filed Jul. 25, 2008, which is assigned to the assignee ofthis application, and which is specifically incorporated herein byreference. For calibration, EHT may simply be selected from within acomfort range such as illustrated in FIG. 3 which depicts comfort ratingon a 1-9 scale on the vertical axis 35 versus EHT in degrees Celsius onthe horizontal axis 37. On an exemplary comfort scale, 1 may beclassified as cold, 2 may be classified as very cool, 3 may beclassified as cool, 4 may be classified as slightly cool, 5 may beclassified as comfortable, 6 may be classified as slightly warm, 7 maybe classified as warm, 8 may be classified as too warm, and 9 may beclassified as hot. A first curve 39 represents cabin warming during coolambient conditions, while a second curve 45 represents cabin coolingduring warm ambient conditions. The discontinuity at the comfort ratingof 5 is due to passengers wearing more clothing when ambienttemperatures are cool and are therefore comfortable at a slightly coolertemperature. On the curves 39, 45 this may place “comfortable” in thearea of 20-24 degrees Celsius depending on season and clothing level. Assuch, EHT may provide a single representative value to characterize anon-uniform thermal environment as a uniform thermal environment thatrelates to occupant thermal sensation.

The EHT may be calculated, or for purposes of calibration in the method30, an EHT may be selected at step 34. EHT for neutral thermal sensationdepends on the occupant metabolic rates and clothing level. In a numberof variations a lookup table may be provided for the EHT set point basedon these, and alternatively other, input parameters for an occupantthermal comfort. The EHT may be determined or selected for purposes ofan example, as a value of 25 degrees Celsius, which may correspond to acomfort rating of approximately 6, being slightly warm. The method 30may then proceed to step 36. Step 36 may receive an input from step 38representative of the cabin temperature set point. With reference toFIG. 4, a calibration curve 44 for EHT set point is illustrated as EHTin degrees Celsius on the vertical axis 46 versus ambient temperature indegrees Celsius on the horizontal axis 48. Ambient temperature T_(a) maybe described as the measured temperature in the external environmentsupplied by the temperature sensor 12 at step 40. The calibration curvemay be a constant value of 22 degrees Celsius, regardless of ambienttemperature. The value of 22 degrees may be provided from step 38 tostep 36. Step 36 may subtract the set point of 22 degrees provided fromstep 38 from the EHT of 25 degrees provided from step 34 and may providea control error or ΔEHT. In the example, the control error of 25−22=3 isprovided from step 36 to step 42 and indicates that the HVAC system mustadjust the cabin temperature down three degrees. The control error of 3may be provided as a signal at 41. At step 42 the cabin EHT control maydetermine a control value Y_(n)=10·T_(a)+Y_(pi)(ΔT_(c)) that may be acombination of steady state (10·T_(a)), and transient (Y_(pi)(ΔT_(c))),temperature based components. T_(a) may be measured ambient temperature,ΔT_(c) may be measured change in cabin temperature, and Y_(pi) may be aproportional-plus-integral control value. The control value Y_(pi) maybe determined by K(T_(sp)−T_(c))+K/T_(i)∫(T_(sp)−T_(c))dτ, where K is aproportional gain constant and K/T_(i) is integral gain. In a number ofvariations the control value may be read from a lookup table by thecontroller 20 where a list of control values are listed by control errorvalue. The determined control value Y_(n) may be provided from step 42to step 43 where signals may be sent to the HVAC system to set adischarge air temperature 24, HVAC blower speed 22, and HVAC mode 26.Feedback provided by the sensors may be used to adjust the control valueas the cabin temperature approaches the set point temperature.

The following description of variants is only illustrative ofcomponents, elements, acts, products and methods considered to be withinthe scope of the invention and are not in any way intended to limit suchscope by what is specifically disclosed or not expressly set forth. Thecomponents, elements, acts, products and methods as described herein maybe combined and rearranged other than as expressly described herein andstill are considered to be within the scope of the invention.

Variation 1 may involve a method of providing automatic climate control.A set point temperature input setting may be read. A cabin equivalenthomogeneous temperature may be compared to the set point temperature. Acontrol value may be determined to equalize the cabin equivalenthomogeneous temperature with the set point temperature.

Variation 2 may include the method according to variation 1 and mayinclude calibration using a fixed set point temperature regardless ofthe ambient temperature.

Variation 3 may include the method according to variation 2 and mayinclude selecting the fixed set point temperature based on a comfortrating.

Variation 4 may include the method according to variation 1 and mayinclude providing a blower and a mode controller, and controlling theblower and the mode controller using the control value.

Variation 5 may include the method according to variation 1 and mayinclude determining a steady state control value component, determininga transient control value component and combining the steady statecontrol value component and the transient control value component.

Variation 6 may include the method according to variation 1 and mayinclude sensing an ambient temperature, sensing a cabin temperature andusing the ambient temperature and the cabin temperature to generate thecontrol value.

Variation 7 may include the method according to variation 1 and mayinclude setting a blower speed, setting a discharge temperature, andsetting an HVAC mode, all based on the cabin equivalent homogeneoustemperature and the set point temperature.

Variation 8 may include the method according to variation 1 and mayinclude determining a control error based on a difference between thecabin equivalent homogeneous temperature and the set point temperature.

Variation 9 may involve method of providing automatic climate control ofa heating, ventilating and air conditioning system. A set pointtemperature input may be read. A cabin equivalent homogeneoustemperature may be calculated. The cabin equivalent homogeneoustemperature may be compared to the set point temperature. A controlvalue may be generated to equalize the cabin equivalent homogeneoustemperature with the set point temperature.

Variation 10 may include the method according to variation 9 and mayinclude calibrating using a fixed set point temperature regardless ofthe ambient temperature.

Variation 11 may include the method according to variation 10 whereinthe fixed set point temperature may be 22 degrees Celsius.

Variation 12 may include the method according to variation 9 and mayinclude providing a blower and a mode controller, and controlling theblower and the mode controller using the control value.

Variation 13 may include the method according to variation 9 and mayinclude determining a steady state control value component, determininga transient control value component and combining the steady statecontrol value component and the transient control value component.

Variation 14 may include the method according to variation 9 and mayinclude sensing an ambient temperature, sensing a cabin temperature andusing the ambient temperature and the cabin temperature to generate thecontrol value.

Variation 15 may include the method according to variation 9 and mayinclude setting a blower speed, setting a discharge temperature, andsetting an HVAC mode all based on the cabin equivalent homogeneoustemperature and the set point temperature.

Variation 16 may include the method according to variation 9 and mayinclude determining a control error based on a difference between thecabin equivalent homogeneous temperature and the set point temperature.

Variation 17 may involve a method of controlling an HVAC system. A setpoint temperature input may be read. A cabin equivalent homogeneoustemperature may be obtained. The cabin equivalent homogeneoustemperature may be compared to the set point temperature. A controlerror based on a difference between the cabin equivalent homogeneoustemperature and the set point temperature may be generated. A controlvalue may be determined based on the control error. The HVAC system maybe adjusted based on the control value.

Variation 18 may include the method according to variation 17 and mayinclude determining a steady state control value component, determininga transient control value component and combining the steady statecontrol value component and the transient control value component toobtain the control value.

Variation 19 may include the method according to variation 17 and mayinclude sensing an ambient temperature, sensing a cabin temperature andusing the ambient temperature and the cabin temperature to determineboth the steady state control value component and the transient controlvalue component.

Variation 20 may include the method according to variation 17 and mayinclude setting a blower speed, setting a discharge temperature, andsetting an HVAC mode all based on the cabin equivalent homogeneoustemperature and the set point temperature.

The above description of select variations within the scope of theinvention is merely illustrative in nature and, thus, variations orvariants thereof are not to be regarded as a departure from the spiritand scope of the invention.

What is claimed is:
 1. A method of providing automatic climate controlcomprising reading a set point temperature input, comparing a cabinequivalent homogeneous temperature to the set point temperature, andgenerating a control value to equalize the cabin equivalent homogeneoustemperature with the set point temperature.
 2. The method according toclaim 1 further comprising calibrating using a fixed set pointtemperature regardless of the ambient temperature.
 3. The methodaccording to claim 2 further comprising selecting the fixed set pointtemperature based on a comfort rating.
 4. The method according to claim1 further comprising providing a blower and a mode controller, andcontrolling the blower and the mode controller using the control value.5. The method according to claim 1 further comprising determining asteady state control value component, determining a transient controlvalue component and combining the steady state control value componentand the transient control value component.
 6. The method according toclaim 1 further comprising sensing an ambient temperature, sensing acabin temperature and using the ambient temperature and the cabintemperature to generate the control value.
 7. The method according toclaim 1 further comprising setting a blower speed, setting a dischargetemperature, and setting an HVAC mode all based on the cabin equivalenthomogeneous temperature and the set point temperature.
 8. The methodaccording to claim 1 further comprising determining a control errorbased on a difference between the cabin equivalent homogeneoustemperature and the set point temperature.
 9. A method of providingautomatic climate control of a heating, ventilating and air conditioningsystem comprising reading a set point temperature input, calculating acabin equivalent homogeneous temperature, comparing the cabin equivalenthomogeneous temperature to the set point temperature, and generating acontrol value to equalize the cabin equivalent homogeneous temperaturewith the set point temperature.
 10. The method according to claim 9further comprising calibrating using a fixed set point temperatureregardless of the ambient temperature.
 11. The method according to claim10 wherein the fixed set point temperature is 22 degrees Celsius. 12.The method according to claim 9 further comprising providing a blowerand a mode controller, and controlling the blower and the modecontroller using the control value.
 13. The method according to claim 9further comprising determining a steady state control value component,determining a transient control value component and combining the steadystate control value component and the transient control value component.14. The method according to claim 9 further comprising sensing anambient temperature, sensing a cabin temperature, and using the ambienttemperature and the cabin temperature to generate the control value. 15.The method according to claim 9 further comprising setting a blowerspeed, setting a discharge temperature, and setting an HVAC mode allbased on the cabin equivalent homogeneous temperature and the set pointtemperature.
 16. The method according to claim 9 further comprisingdetermining a control error based on a difference between the cabinequivalent homogeneous temperature and the set point temperature.
 17. Amethod of controlling an HVAC system comprising reading a set pointtemperature input, obtaining a cabin equivalent homogeneous temperature,comparing the cabin equivalent homogeneous temperature to the set pointtemperature, generating a control error based on a difference betweenthe cabin equivalent homogeneous temperature and the set pointtemperature, determining a control value based on the control error, andadjusting the HVAC system based on the control value.
 18. The methodaccording to claim 17 further comprising determining a steady statecontrol value component, determining a transient control value componentand combining the steady state control value component and the transientcontrol value component to obtain the control value.
 19. The methodaccording to claim 9 further comprising sensing an ambient temperature,sensing a cabin temperature and using the ambient temperature and thecabin temperature to determine both the steady state control valuecomponent and the transient control value component.
 20. The methodaccording to claim 17 further comprising setting a blower speed, settinga discharge temperature, and setting an HVAC mode all based on the cabinequivalent homogeneous temperature and the set point temperature.